This Ghastly Sack of Cells may be your Distant Ancestor

SAY HELLO TO GREAT-GREAT-GREAT-GREAT … GRANDPA

In a paper in Nature, scientists claim to have found humanity’s oldest known ancestor. This horrifying, bag-like sea creature lived about 540 million years ago and was recently dug up in China.

Technically, the oldest known fossils go way farther back, to about 3.5 billion years. But those were cyanobacteria, and although we’re related to them, those photosynthetic creatures are on a different branch of Earth’s family tree.

The new fossil, named Saccorhytus, appears to be the oldest deuterostome found to date. Deuterostomes are a group of animals that includes vertebrates (that’s us) as well as starfish and other echinoderms. The group is defined by how its embryos develop: the first opening that forms in each tiny ball of cells becomes the organism’s anus. It’s a glamorous family legacy, to be sure.